This invention relates to spiral wound containers for packaging fluid products, especially those which must be maintained under substantial pressure. More particularly, this invention is directed at an improved closure for such containers. This novel closure, simple to construct and insert, affords an effective liquid and pressure tight seal.
Spiral wound containers have been available for many years and a variety of methods and apparatus have been devised for making such containers, for example U.S. Pat. Nos. 2,261,621, 2,623,443, 2,623,445, 3,178,088, 3,428,239, 3,608,771, and British patent specification No. 428,909. These containers have a number of advantages, the principal one of which is their economy as compared to more standard containers.
This attribute is of special import in containers for the shipping of fluids under pressure. These fluids such as soft drink syrups, carbonated beverages or beers, chemicals, gases or other liquids commonly are shipped to the point of consumption or use in stainless steel shipping dispensers. These metal dispensers are very costly to purchase and their return rate, necessitated by their high fabrication cost, is both low and expensive to accomplish. The replacement of such metal containers with a spiral wound construction beneficially advantages both these prior limitations. The costs of fabrication are so substantially reduced that the containers are economically disposable. The disposability avoids the costs of pick-up and return.
However, prior art disposable spiral wound containers for such fluids have not been wholly successful. Rather, they have displayed an inability to retain the necessary internal pressure of the packaged fluid. This disadvantage has inhered in both the side walls used to fabricate the usually tubular containers and in the final sealing of such tubes by end closure thereof. This time dependent leakage substantially decreases shelf life and limits the use of these packages in pressurized fluid applications.
Although side wall construction has been substantially improved, such as in U.S. Pat. Nos. 3,428,239 and 3,608,771, as to be capable of better retaining these internal fluid pressures, the end closures and methods thereof still display less than optimum economy and utility. Rather, prior leak-proof closures and methods thereof, disclosed for example by U.S. Pat. Nos. 2,261,621, 3,021,974, 3,178,088, 3,428,239, 3,664,540, and British patent specification No. 428,909, are complex and substantially blunt that economy fostered by disposable spiral wound packaging.